JP2014102446A - Toner for electrostatic charge image development - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner for electrostatic charge image development that can be suitably fixed to a recording medium within a wide temperature range, and has excellent heat-resistant storage stability and mechanical strength.SOLUTION: A toner for electrostatic charge image development comprises toner core particles including at least a binder resin, and each of the toner core particles is covered with a shell layer. The shell layer is formed of an inner layer and an outer layer; and when a difference between an SP value (SP) of the binder resin and an SP value (SP) of the inner layer is ΔSP, and a difference between the SP value of the inner layer (SP) and an SP value (SP) of the outer layer is ΔSP, ΔSPand ΔSPare respectively within a predetermined range, and ΔSPis less than ΔSP.

Description

  The present invention relates to a toner for developing an electrostatic image.

  Regarding toner, from the viewpoints of energy saving and downsizing of the apparatus, a toner having excellent low-temperature fixability that can be satisfactorily fixed without heating the fixing roller as much as possible is desired. However, toners with excellent low-temperature fixability often use a binder resin with a low melting point or glass transition point or a release agent with a low melting point, and generally tend to aggregate when stored at high temperatures. . When aggregation occurs in the toner, there is a problem that, when an image is formed, an image defect due to toner adhesion to the developing sleeve or the photosensitive drum or a fog due to toner charging failure occurs in the formed image. .

  Therefore, in order to deal with the above-mentioned problems, the purpose is to obtain a toner having excellent fixability at a wide temperature range, the purpose of improving the storage stability of the toner at a high temperature, and the purpose of improving the blocking resistance of the toner. A core-shell structure in which the core particles containing a low-melting binder resin are coated with a shell layer made of a resin having a Tg higher than the glass transition point (Tg) of the binder resin contained in the core particles. Toner is used.

  As a toner having such a core-shell structure, a crystalline polyester resin having an intermediate layer and a shell layer on the core particle surface, the intermediate layer containing wax, and a shell layer having a softening point of 60 ° C. or higher and 120 ° C. or lower is used. A toner containing 70% by mass or more and 100% by mass or less in the shell layer has been proposed (see Patent Document 1).

JP 2005-099081 A

  However, since the toner described in Patent Document 1 selects a material having relatively low mechanical strength as the material for the intermediate layer and the shell layer, the shell layer and the intermediate layer are used when the toner is subjected to mechanical stress. It is easy to collapse. When the shell layer and the intermediate layer are crushed, a component such as a release agent is exposed on the surface of the toner particles, and the toner tends to aggregate when the toner is stored at a high temperature.

  The present invention has been made in view of the above problems, and provides an electrostatic charge image developing toner that is satisfactorily fixed on a recording medium in a wide temperature range, and has excellent heat-resistant storage stability and mechanical strength. Objective.

For the toner for developing an electrostatic charge image comprising toner core particles containing at least a binder resin and a shell layer covering the toner core particles, the present inventors comprise a shell layer comprising an inner layer and an outer layer. The SP value (SP _c ), the SP value (SP _t ) of the inner layer, and the SP value (SP _s ) of the outer layer satisfy the predetermined relationship, and the above problem can be solved. The invention has been completed. Specifically, the present invention provides the following.

The present invention
A toner core particle containing at least a binder resin, and a shell layer covering the toner core particle,
The shell layer is composed of an inner layer and an outer layer,
ΔSP ₁ (SP _c −SP _t ), which is the difference between the SP value (SP _c ) of the binder resin and the SP value (SP _t ) of the material of the inner layer, is 0.3 or more and 1.4 or less. ,
ΔSP ₂ (SP _t −SP _s ), which is the difference between the material SP value (SP _t ) of the inner layer and the SP value (SP _s ) of the material of the outer layer, is 0.5 or more and 1.6 or less,
The present invention relates to an electrostatic charge image developing toner in which ΔSP ₁ is less than ΔSP ₂ .

  According to the present invention, it is possible to provide a toner for developing an electrostatic image that is satisfactorily fixed on a recording medium in a wide temperature range, and has excellent heat-resistant storage stability and mechanical strength.

  Hereinafter, embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the object of the present invention. In addition, although description may be abbreviate | omitted suitably about the location where description overlaps, the summary of invention is not limited.

  The electrostatic image developing toner of the present invention (hereinafter also simply referred to as toner) comprises toner core particles containing at least a binder resin and a shell layer covering the toner core particles. The shell layer is composed of an inner layer and an outer layer. The binder resin, inner layer, and outer layer solubility parameters (hereinafter also simply referred to as SP values) have values in a predetermined range. Hereinafter, the SP value defined in the present invention and the electrostatic image developing toner of the present invention will be described.

<< SP value >>
The SP value defined in the present invention is a value represented by the square root of the molecular cohesive energy. F. It can be calculated by the method described in Fedors, Polymer Engineering Science, 14, p147 (1974). The unit is (MPa) ^1/2 and indicates a value at 25 ° C.

Hereinafter, the SP value of the binder resin is SP _c , the SP value of the material of the inner layer of the shell layer is SP _t, and the SP value of the material of the outer layer of the shell layer is SP _s . In addition, the difference between SP _c and SP _t is ΔSP ₁ , and the difference between SP _t and SP _s is ΔSP ₂ . When the toner of the present invention is prepared, SP _c , SP _t , and SPs have the following relationship with respect to the binder resin, the material of the inner layer of the shell layer, and the material of the outer layer of the shell layer:
0.3 ≦ SP _c −SP _t (ΔSP ₁ ) ≦ 1.4,
0.5 ≦ SP _t −SP _s (ΔSP ₂ ) ≦ 1.6, and SP _c −SP _t (ΔSP ₁ ) <SP _t −SP _s (ΔSP ₂ ),
Meet.

When SP _c , SP _t , and SP _s satisfy the above relationship, it is possible to obtain a toner that is satisfactorily fixed to a recording medium in a wide temperature range and that has excellent heat-resistant storage stability and mechanical strength. .

If ΔSP ₁ is too small, the toner core particles and the inner layer of the shell layer are easily compatible with each other, and a component such as a release agent that has migrated from the toner core particles to the inner layer of the shell layer is present at the interface between the inner layer and the outer layer of the shell layer. May be exposed. In this case, since the inner layer and the outer layer of the shell layer are easily peeled, the strength of the shell layer is likely to decrease. When the strength of the shell layer is lowered, it becomes difficult to obtain a toner having excellent heat storage stability and mechanical strength.

When ΔSP ₁ is too large, the toner core particles and the inner layer of the shell layer are hardly compatible, so that the shell layer is easily peeled off from the toner core particles due to mechanical stress, and the mechanical strength of the toner is impaired. On the other hand, if ΔSP ₁ is too large, the obtained toner may be difficult to be satisfactorily fixed on the recording medium in a low temperature range.

When ΔSP ₂ is too small, the inner layer and the outer layer of the shell layer are easily compatible with each other and firmly adhered to each other, so that the strength of the shell layer tends to be excessively high. When the strength of the shell layer is excessively high, the shell layer is not easily crushed when the toner is fixed to the paper, and the low-temperature fixability of the toner is likely to be impaired.

If whose ASP ₂ is too large, the inner layer and is hardly compatible with the outer layer of the shell layer, and the inner layer and the outer layer of the shell layer satisfactorily hard adhesive. For this reason, as the strength of the shell layer decreases, the heat resistant storage stability and mechanical strength of the toner tend to be impaired.

≪Toner for electrostatic image development≫
The toner of the present invention comprises toner core particles and a shell layer that coats the toner core particles. The toner of the present invention may have an external additive attached to the surface as necessary. The toner of the present invention can be mixed with a desired carrier and used as a two-component developer. Hereinafter, toner core particles and shell layers constituting the toner of the present invention, an external additive as an optional component, a carrier used when the toner of the present invention is used as a two-component developer, and the toner of the present invention The manufacturing method will be described in order.

[Toner core particles]
The toner core particles constituting the toner of the present invention include at least a binder resin. The toner core particles may contain components such as a colorant, a release agent, and a charge control agent, if desired, in addition to the binder resin. Hereinafter, the binder resin, the release agent, the colorant, and the charge control agent that are essential or optional components of the toner core particles will be described in order.

[Binder resin]
Binder resin contained in the toner core of the toner of the present invention, the SP _c, and SP _t, and SP _s is, as long as a predetermined relationship described above is not particularly limited.

  Specific examples of the binder resin include styrene resin, acrylic resin, styrene acrylic resin, polyethylene resin, polypropylene resin, vinyl chloride resin, polyester resin, polyamide resin, polyurethane resin, polyvinyl alcohol resin, vinyl ether. And thermoplastic resins such as styrene resins, N-vinyl resins, and styrene-butadiene resins. Among these resins, a styrene acrylic resin and a polyester resin are preferable, and a polyester resin is more preferable in terms of dispersibility of the colorant in the toner, toner chargeability, and toner fixing property to the paper. Hereinafter, the styrene acrylic resin and the polyester resin used in this embodiment will be described.

  The styrene acrylic resin is a copolymer of a styrene monomer and an acrylic monomer. Specific examples of the styrene monomer include styrene, α-methylstyrene, vinyl toluene, α-chlorostyrene, o-chlorostyrene, m-chlorostyrene, p-chlorostyrene, and p-ethylstyrene. Specific examples of the acrylic monomer include methyl acrylate, ethyl acrylate, n-propyl acrylate, iso-propyl acrylate, n-butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, meta Examples include (meth) acrylic acid alkyl esters such as methyl acrylate, ethyl methacrylate, n-butyl methacrylate, and iso-butyl methacrylate.

When using a styrene-acrylic resin as the binder resin, SP _c can be adjusted by increasing or decreasing the amount of the (meth) acrylic acid in preparing the (meth) acrylic resin.

  When a polyester resin is used as the binder resin, it is easy to prepare a toner that can be satisfactorily fixed over a wide temperature range and has excellent color developability. As the polyester resin, those obtained by condensation polymerization or co-condensation polymerization of a divalent or trivalent or higher alcohol component and a divalent or trivalent or higher carboxylic acid component can be used. The components used when synthesizing the polyester resin include the following alcohol components and carboxylic acid components.

  Specific examples of the divalent or trivalent or higher alcohol component include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butanediol, neopentyl glycol, 1 Diols such as 1,4-butenediol, 1,5-pentanediol, 1,6-hexanediol, 1,4-cyclohexanedimethanol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol; bisphenol A Bisphenols such as hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylenated bisphenol A; sorbitol, 1,2,3,6-hexanetetrol, 1,4-sol Tan, pentaerythritol, dipentaerythritol, tripentaerythritol, 1,2,4-butanetriol, 1,2,5-pentanetriol, glycerol, diglycerol, 2-methylpropanetriol, 2-methyl-1,2, Examples include trivalent or higher alcohols such as 4-butanetriol, trimethylolethane, trimethylolpropane, and 1,3,5-trihydroxymethylbenzene.

  Specific examples of the divalent or trivalent or higher carboxylic acid component include maleic acid, fumaric acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, Sebacic acid, azelaic acid, malonic acid, or n-butyl succinic acid, n-butenyl succinic acid, isobutyl succinic acid, isobutenyl succinic acid, n-octyl succinic acid, n-octenyl succinic acid, n-dodecyl succinic acid, n-dodecenyl succinic acid Divalent carboxylic acids such as acids, isododecyl succinic acid, alkyl such as isododecenyl succinic acid or alkenyl succinic acid; 1,2,4-benzenetricarboxylic acid (trimellitic acid), 1,2,5- Benzenetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4 Naphthalenetricarboxylic acid, 1,2,4-butanetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylenecarboxypropane, 1,2,4-cyclohexanetricarboxylic acid , A trivalent or higher carboxylic acid such as tetra (methylenecarboxyl) methane, 1,2,7,8-octanetetracarboxylic acid, pyromellitic acid, and empole trimer acid. As these divalent or trivalent or higher carboxylic acid components, acid halides, acid anhydrides, and ester-forming derivatives of lower alkyl esters may be used. Here, “lower alkyl” means an alkyl group having 1 to 6 carbon atoms.

When the binder resin is a polyester resin, the acid value is not particularly limited as long as SP _c , SP _t , and SP _s satisfy the above-described predetermined relationship. The acid value of the polyester resin is preferably 10 mgKOH / g or more and 40 mgKOH / g or less. If the acid value is too low, when the toner is prepared by the aggregation method described later, when the fine particles of the components contained in the toner are aggregated, the aggregation of the fine particles may not easily proceed well. If it is too high, various performances of the toner may be impaired due to the influence of humidity under high humidity conditions. The acid value of the polyester resin can be adjusted by adjusting the balance between the hydroxyl group of the alcohol component used for the synthesis of the polyester resin and the carboxyl group of the carboxylic acid component.

When using a polyester resin as the binder resin, SP _c is obtained by adjusting the balance between the amount of hydroxyl groups of the alcohol component used in the synthesis of the polyester resin and the amount of carboxyl groups of the carboxylic acid component. Can be adjusted.

  As the binder resin, not only a thermoplastic resin can be used alone, but also a resin obtained by adding a crosslinking agent or a thermosetting resin to the thermoplastic resin can be used. By introducing a partially crosslinked structure into the binder resin, the storage stability, shape retention, and durability of the toner can be improved without deteriorating the toner fixability.

  As the thermosetting resin that can be used together with the thermoplastic resin, an epoxy resin or a cyanate resin is preferable. Specific examples of suitable thermosetting resins include bisphenol A type epoxy resins, hydrogenated bisphenol A type epoxy resins, novolac type epoxy resins, polyalkylene ether type epoxy resins, cycloaliphatic type epoxy resins, and cyanate resins. . These thermosetting resins can be used in combination of two or more.

  The glass transition point (Tg) of the binder resin is preferably 45 ° C. or higher and 70 ° C. or lower. If the glass transition point of the binder resin is too low, the toner may be fused inside the developing portion of the image forming apparatus, or the storage stability of the toner may be reduced. In some cases, the toners are partially fused when stored in a warehouse. On the other hand, if the glass transition point of the binder resin is too low, the strength of the polyester resin is reduced, and the toner tends to adhere to the latent image carrying portion. If the glass transition point of the binder resin is too high, the toner tends to be difficult to fix well at low temperatures.

  In addition, the glass transition point of binder resin can be calculated | required from the change point of specific heat of binder resin using a differential scanning calorimeter (DSC) based on JISK7121. A more specific measuring method is as follows. It can obtain | require by measuring the endothermic curve of binder resin using the differential scanning calorimeter DSC-6200 by Seiko Instruments Inc. as a measuring apparatus. 10 mg of a measurement sample is put in an aluminum pan, and an empty aluminum pan is used as a reference. Obtaining the glass transition point of the binder resin using the endothermic curve of the binder resin obtained by measurement under the conditions of a measurement temperature range of 25 ° C. or more and 200 ° C. or less, a heating rate of 10 ° C./min, and normal temperature and normal humidity. Can do.

  The melting point (Tm) of the binder resin is preferably 80 ° C. or higher and 120 ° C. or lower. If the melting point of the binder resin is too high, it may be difficult to fix the toner well at a low temperature. If the melting point of the binder resin is too low, the toner may agglomerate during storage at a high temperature, and the heat resistant storage stability of the toner may be impaired.

  The number average molecular weight (Mn) of the binder resin is preferably 1,000 or more and 4,000 or less, and more preferably 1,500 or more and 3,000 or less. Further, the weight average molecular weight (Mw) of the binder resin is preferably 1,500 to 11,000, more preferably 3,500 to 7,000. Further, the molecular weight distribution (Mw / Mn) represented by the ratio of the number average molecular weight (Mn) to the mass average molecular weight (Mw) is preferably 2 or more and 10 or less. By setting the molecular weight distribution of the binder resin within such a range, it becomes easy to obtain a toner having excellent low-temperature fixability. The number average molecular weight (Mn) and the mass average molecular weight (Mw) of the binder resin can be measured using gel permeation chromatography.

SP _c is not particularly limited as long as SP _c , SP _t , and SP _s satisfy the aforementioned predetermined relationship. SP _c is preferably 11.0 or more and 12.0 or less. By setting SP _c within such a range, ΔSP ₁ (SP _c −SP _t ) can be easily adjusted within a range of 0.3 to 1.4.

As a preferred method for producing the toner of the present invention, an agglomeration method described later is exemplified. When a polyester resin is used as the binder resin when the toner is produced by the aggregation method, it is preferable to use a polyester resin that has been subjected to a treatment for reducing the oligomer content in the toner as measured by a predetermined method. . By doing so, it becomes easy to contain a desired amount of a release agent in the toner core particles, and it is easy to obtain a toner having excellent low-temperature fixability.
In the specification of the present application, a polyester resin that has been subjected to a treatment that removes at least a part of the oligomer contained in the polyester resin or a treatment that reduces the amount of oligomer produced in the synthesis stage is referred to as a “low oligomer polyester resin”. Called.

  As a method of removing at least a part of the oligomer having a molecular weight of 1000 or less contained in the polyester resin, a method of treating the pulverized polyester resin with an aqueous solution of a basic substance, if necessary, or a molecular weight in the polyester resin The method of processing using the organic solvent which can selectively melt | dissolve the low molecular weight component 1000 or less is mentioned. Among these methods, a method of treating the polyester resin with an aqueous solution of a basic substance is preferable in that the removal efficiency of the oligomer in the polyester resin is high. Specific examples of the basic substance include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, and alkali metal carbonates such as sodium carbonate and potassium carbonate. Two or more basic substances may be used in combination.

  The amount of the oligomer having a molecular weight of 1000 or less contained in the polyester resin is not particularly limited, but the amount of the oligomer having a molecular weight of 1000 or less based on the mass of the toner in the toner is preferably 1000 ppm by mass or less.

<Measurement method of oligomer content in toner (methanol extraction method)>
The content A (mass ppm) of the oligomer having a molecular weight of 1000 or less derived from the binder resin in the toner is:
The following steps (1) to (3):
(1) A step of obtaining a methanol extract containing a binder resin-derived oligomer by stirring 100 g of a sample of electrostatic latent image developing toner in 500 g of methanol at 60 ° C. for 8 hours;
(2) Among the oligomers contained in the methanol extract, the content of the oligomer having a molecular weight of 1000 or less in the methanol extract is measured, and the mass B (g) of the oligomer having a molecular weight of 1000 or less contained in the total amount of the methanol extract. And (3) the following formula:
A = (B / 100) × 1000000,
A step of calculating a content A (mass ppm) of an oligomer having a molecular weight of 1000 or less in the toner based on the toner mass,
Can be measured according to the method consisting of

  The method for measuring the amount of oligomer having a molecular weight of 1000 or less among the oligomers contained in the methanol extract is not particularly limited. The amount of the oligomer having a molecular weight of 1000 or less contained in the methanol extract is determined by infrared spectroscopy (IR), ultraviolet spectroscopy, nuclear magnetic resonance spectroscopy (NMR), high performance liquid chromatography (HPLC), gel permeation chromatography ( GPC) and mass spectrometry can be used for analysis. Especially, it is preferable to measure the quantity of the oligomer of molecular weight 1000 or less using GPC. Hereinafter, a method for measuring the amount of oligomer having a molecular weight of 1000 or less using GPC will be described.

(Measurement method of oligomer amount with molecular weight of 1000 or less using GPC)
Tetrahydrofuran (THF) is used as a solvent, and a sample to be measured is dissolved in THF at a concentration of preferably 0.1 mg / ml to 5 mg / ml, more preferably 0.5 mg / ml to 2 mg / ml. As a method for dissolving the sample in THF, there are a method of stirring the sample in THF and a method of immersing the sample in THF in an ultrasonic bath. Thereafter, the obtained THF solution is filtered with a sample processing filter to obtain a measurement sample used for GPC measurement. The GPC is measured by stabilizing the column at 40 ° C. and flowing a THF solution at a flow rate of 0.35 ml / min under the temperature condition. The molecular weight distribution of the sample is measured as a styrene equivalent molecular weight using a calibration curve prepared using several types of monodisperse polystyrene. It is preferable to measure at least 10 points in order to increase the accuracy of the calibration curve. As the detector, an RI (refractive index) detector or a UV (ultraviolet) detector can be used, but it is preferable to use an RI detector in that detection is possible regardless of the composition of the sample. As a column, a standard polystyrene gel column can be used in combination.

GPC of monodisperse standard polystyrene having a number average molecular weight of 1000 is measured to determine the retention capacity (ml) at the peak position, and this is defined as RVS. GPC of the residue obtained by distilling off the methanol component from the methanol extract is measured and calculated as the ratio of the area of the low molecular side peak portion below RVS to the area of the entire peak of the GPC chromatogram. At this time, a differential refractometer is usually used as the detector. However, only the oligomer portion is separately collected by preparative liquid chromatography, and the monomer composition is pyrolyzed by gas chromatography, infrared spectrometer and proton nucleus. Check with a magnetic resonance measuring device. At this time, when the composition of the entire copolymer is exactly the same, the peak area ratio can be expressed as a weight ratio on the assumption that there is no difference in the refractive index between the oligomer portion and the entire copolymer. The amount of oligomer having a molecular weight of 1000 or less is obtained by calculating the ratio of the peak area of the chromatogram as a percentage.
<GPC measurement conditions>
Apparatus: HLC-8320 (manufactured by Tosoh Corporation)
Eluent: THF (tetrahydrofuran)
Column: TSKgel SuperMultipore HZ-M (manufactured by Tosoh Corporation)
Number of columns: 3 detectors: RI
Eluent flow rate: 0.35 ml / min Sample concentration: 2.0 g / liter Column temperature: 40 ° C.
Sample volume: 10 microliter sample preparation: Prepare with eluent. Shake for 1 hour using a shaker, then filter using a filter (pore size 5 microns).
Calibration curve: Prepared using standard polystyrene

  When the polyester resin is a resin synthesized using a monomer containing an aromatic ring such as polyoxyethylenated bisphenol A and polyoxypropylenated bisphenol A, the content of oligomers having a predetermined molecular weight or less in methanol As a method for measuring, a method using high performance liquid chromatography equipped with a UV detector is preferable.

[Colorant]
The toner core particles may contain a colorant as necessary. As the colorant, a known pigment or dye can be used in accordance with the color of the toner particles. Specific examples of suitable colorants that can be added to the toner include the following colorants.

  Examples of the black colorant include carbon black. Specifically, Raven 1060, 1080, 1170, 1200, 1250, 1255, 1500, 2000, 3500, 5250, 5750, 7000, 5000, ULTRAII, 1190 ULTRAII, manufactured by Columbian Carbon; Black PearlsL, Moguul, manufactured by Cabot -L, Regal 400R, 660R, 330R, Monarch 800, 880, 900, 1000, 1300, 1400; Color Black FW1, FW2, FW200, 18, S160, S170, Special Black 4, 4A, 6, Printex35, U manufactured by Degussa 140U, V, 140V; No. manufactured by Mitsubishi Chemical Corporation. 25, 33, 40, 47, 52, 900, 2300, MCF-88, MA600, 7, 8, 100. Further, as the black colorant, a colorant that is toned to black using a colorant such as a yellow colorant, a magenta colorant, and a cyan colorant, which will be described later, can also be used. Examples of the color toner colorant include a yellow colorant, a magenta colorant, and a cyan colorant.

  Examples of yellow colorants include condensed azo compounds, isoindolinone compounds, anthraquinone compounds, azo metal complexes, methine compounds, and allylamide compounds. Specifically, C.I. I. Pigment Yellow 12, 13, 14, 15, 17, 62, 74, 83, 93, 94, 95, 97, 109, 110, 111, 120, 127, 128, 129, 147, 151, 154, 155, 168, 174, 175, 176, 180, 181, 191 and 194.

  Examples of the magenta colorant include condensed azo compounds, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, basic dye lake compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, and perylene compounds. Specifically, C.I. I. Pigment Red 2, 3, 5, 6, 7, 19, 23, 48: 2, 48: 3, 48: 4, 57: 1, 81: 1, 122, 144, 146, 150, 166, 169, 177, 184, 185, 202, 206, 220, 221 and 254.

  Examples of cyan colorants include copper phthalocyanine compounds, copper phthalocyanine derivatives, anthraquinone compounds, and basic dye lake compounds. Specifically, C.I. I. Pigment blue 1, 7, 15, 15: 1, 15: 2, 15: 3, 15: 4, 60, 62, 66.

  These colorants can be used alone or in combination. The amount of the colorant used is preferably 3% by mass or more and 15% by mass or less with respect to the mass of the toner.

〔Release agent〕
The toner core particles of the toner of the present invention may contain a release agent for the purpose of improving the toner fixability and offset resistance. The type of release agent is not particularly limited as long as it is conventionally used as a release agent for toner.

  Suitable mold release agents include low molecular weight polyethylene, low molecular weight polypropylene, polyolefin copolymers, polyolefin waxes, microcrystalline waxes, paraffin waxes, and aliphatic hydrocarbon waxes such as Fischer-Tropsch wax; oxidized polyethylene waxes, and Oxides of aliphatic hydrocarbon waxes such as block copolymers of oxidized polyethylene waxes; plant waxes such as candelilla wax, carnauba wax, wood wax, jojoba wax, and rice wax; beeswax, lanolin, and whale Animal waxes such as waxes; mineral waxes such as ozokerite, ceresin, and vetrolactam; waxes based on fatty acid esters such as montanate ester wax and castor wax; Some fatty acid esters such as acid carnauba wax, or wax deoxidizing the like all.

  Suitable release agents further include saturated linear fatty acids such as palmitic acid, stearic acid, montanic acid, and long-chain alkyl carboxylic acids having a long-chain alkyl group; brassic acid, eleostearic acid And unsaturated fatty acids such as valinalic acid; saturated alcohols such as stearyl alcohol, eicosyl alcohol, behenyl alcohol, carnauvyl alcohol, seryl alcohol, melyl alcohol, and long chain alkyl alcohols having long chain alkyl groups Polyhydric alcohols such as sorbitol; fatty acid amides such as linoleic acid amide, oleic acid amide, and lauric acid amide; methylene bis stearic acid amide, ethylene biscapric acid amide, ethylene bis lauric acid amide, and hexamethylene vinyl Saturated fatty acid bisamides such as stearic acid amides; Unsaturated fatty acids such as ethylene bisoleic acid amides, hexamethylene bisoleic acid amides, N, N′-dioleyl adipic acid amides, N, N′-dioleyl sebacic acid amides Aromatic bisamides such as amides, m-xylene bis-stearic amide, and N, N′-distearylisophthalic amide; fatty acid metal salts such as calcium stearate, calcium laurate, zinc stearate, and magnesium stearate A wax obtained by grafting a vinyl monomer such as styrene or acrylic acid to an aliphatic hydrocarbon wax; a partially esterified product of a fatty acid such as behenic monoglyceride and a polyhydric alcohol; hydrogenating vegetable oils and fats; Hydro obtained by And methyl ester compounds having a sill group.

  Specifically, the amount of the release agent used is preferably 8% by mass or more and 20% by mass or less, and more preferably 10% by mass or more and 15% by mass or less with respect to the mass of the toner. When the amount of the release agent used is too small, a desired effect may not be obtained with respect to suppression of occurrence of offset and image smearing in the formed image. On the other hand, when the amount of the release agent used is excessive, the storage stability of the toner may be reduced due to fusion between the toners.

(Charge control agent)
The toner core particles of the toner of the present invention may contain a charge control agent as necessary. The charge control agent improves the stability of the charge level of the toner and the charge rise characteristic that is an indicator of whether the toner can be charged to a predetermined charge level in a short time. Used for gaining purposes. When developing with positively charged toner, a positively chargeable charge control agent is used. When developing with negatively charged toner, a negatively chargeable charge control agent is used.

  The type of charge control agent can be appropriately selected from charge control agents conventionally used in toners. Specific examples of the positively chargeable charge control agent include pyridazine, pyrimidine, pyrazine, orthooxazine, metaoxazine, paraoxazine, orthothiazine, metathiazine, parathiazine, 1,2,3-triazine, 1,2,4-triazine, 1,3,5-triazine, 1,2,4-oxadiazine, 1,3,4-oxadiazine, 1,2,6-oxadiazine, 1,3,4-thiadiazine, 1,3,5-thiadiazine, 1, 2,3,4-tetrazine, 1,2,4,5-tetrazine, 1,2,3,5-tetrazine, 1,2,4,6-oxatriazine, 1,3,4,5-oxatriazine, Azine compounds such as phthalazine, quinazoline and quinoxaline; Azin Fast Red FC, Azin Fast Red 12BK, Azine Violet BO, Azine Direct dyes consisting of azine compounds such as Ng Brown 3G, Azin Light Brown GR, Azin Dark Green BH / C, Azin Deep Black EW, and Azin Deep Black 3RL; Nigrosine such as Nigrosine, Nigrosine Salt, Nigrosine Derivative Compounds; Acid dyes comprising nigrosine compounds such as nigrosine BK, nigrosine NB, nigrosine Z; metal salts of naphthenic acid or higher fatty acids; alkoxylated amines; alkylamides; A class ammonium salt is mentioned. Among these positively chargeable charge control agents, a nigrosine compound is particularly preferable in that a more rapid start-up property can be obtained. These positively chargeable charge control agents can be used in combination of two or more.

  A resin having a quaternary ammonium salt, carboxylate, or carboxyl group as a functional group can also be used as a positively chargeable charge control agent. More specifically, a styrene resin having a quaternary ammonium salt, an acrylic resin having a quaternary ammonium salt, a styrene acrylic resin having a quaternary ammonium salt, a polyester resin having a quaternary ammonium salt, and a carboxylate Styrene resin having carboxylate, acrylic resin having carboxylate, styrene acrylic resin having carboxylate, polyester resin having carboxylate, styrene resin having carboxyl group, acrylic resin having carboxyl group, carboxyl group Styrene acrylic resin having a carboxyl group and polyester resin having a carboxyl group. The molecular weight of these resins is not particularly limited as long as the object of the present invention is not impaired, and may be an oligomer or a polymer.

  Among the resins that can be used as positively chargeable charge control agents, styrene acrylic resins having a quaternary ammonium salt as a functional group are more preferable because the charge amount can be easily adjusted to a value within a desired range. preferable. Specific examples of preferred acrylic comonomers that are copolymerized with styrene units in styrene acrylic resins having a quaternary ammonium salt as a functional group include methyl acrylate, ethyl acrylate, n-propyl acrylate, and iso-propyl acrylate. (Meth) acrylic acid, such as n-butyl acrylate, iso-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate Examples include alkyl esters.

  As the quaternary ammonium salt, a unit derived from a dialkylaminoalkyl (meth) acrylate, dialkylamino (meth) acrylamide, or dialkylaminoalkyl (meth) acrylamide through a quaternization step is used. Specific examples of the dialkylaminoalkyl (meth) acrylate include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, and dibutylaminoethyl (meth) acrylate. A specific example of dialkyl (meth) acrylamide is dimethylmethacrylamide. Specific examples of the dialkylaminoalkyl (meth) acrylamide include dimethylaminopropyl methacrylamide. Further, a hydroxy group-containing polymerizable monomer such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, or N-methylol (meth) acrylamide can be used in combination during polymerization.

  Specific examples of the negatively chargeable charge control agent include organometallic complexes and chelate compounds. Examples of organometallic complexes and chelate compounds include acetylacetone metal complexes such as aluminum acetylacetonate and iron (II) acetylacetonate, and salicylic acid metal complexes such as chromium 3,5-di-tert-butylsalicylate. A salicylic acid metal salt is preferable, and a salicylic acid metal complex or a salicylic acid metal salt is more preferable. These negatively chargeable charge control agents can be used in combination of two or more.

  The use amount of the positively or negatively chargeable charge control agent is typically 1.5 parts by mass or more and 15 parts by mass or less, preferably 2.0 parts by mass when the total amount of the toner is 100 parts by mass. The amount is more preferably 8.0 parts by mass or less, and particularly preferably 3.0 parts by mass or more and 7.0 parts by mass or less. When the amount of charge control agent used is too small, it is difficult to stably charge the toner to a predetermined polarity, so that the image density of the formed image falls below a desired value, or it is difficult to maintain the image density over a long period of time. There are things to do. In such a case, the charge control agent is difficult to uniformly disperse in the toner, so that the formed image is likely to be fogged or the latent image carrier is easily contaminated due to adhesion of the toner component. When the amount of the charge control agent used is excessive, the latent image carrier is caused by image defects in the formed image due to poor charging under high temperature and high humidity due to deterioration of environmental resistance, or due to adhesion of toner components. Contamination is likely to occur.

[Shell layer]
The shell layer constituting the toner of the present invention includes an inner layer and an outer layer. The material of the shell layer can form an inner layer and an outer layer, the first ΔSP value difference (SP _c −SP _t ) is 0.3 or more and 1.4 or less, and the second SP value difference (SP _t −SP _s ) is 0. and at .5 to _1.6, as long as it satisfies the relationship of _{SP c -SP t <SP t -SP} s, not particularly limited. As the material for the shell layer, it is usually preferable to use a resin because it is easy to adjust the SP value (SP _t ) of the inner layer material and the SP value (SP _s ) of the outer layer material. Hereinafter, the inner layer and the outer layer will be described.

[Inner layer]
The material of the inner layer is not particularly limited as long as SP _c , SP _t , and SP _s satisfy the aforementioned predetermined relationship. The inner layer of the material, since the easy to adjust the SP _t, (meth) acrylic resin, a styrene - (meth) acrylic resin, and one or more resins that are selected from the group consisting of polyester resins are preferred. Then, whose ASP ₁ and, since the whose ASP ₂ easily adjusted to a value within a predetermined range, the resin constituting the inner layer polyester resin is more preferable. As the polyester resin suitably used as the resin constituting the inner layer, the same type of resin as the binder resin can be used.

  Hereinafter, the (meth) acrylic resin and the styrene- (meth) acrylic resin that are used as the resin that can constitute the inner layer will be described.

((Meth) acrylic resin)
When a (meth) acrylic resin is used as the resin constituting the inner layer, the (meth) acrylic resin is a resin obtained by polymerizing a monomer containing at least a (meth) acrylic monomer. (Meth) acrylic monomers used for the preparation of (meth) acrylic resins include (meth) acrylic acid; alkyls such as methyl (meth) acrylate, ethyl (meth) acrylate, and propyl (meth) acrylate ( (Meth) acrylates; such as (meth) acrylamide, N-alkyl (meth) acrylamide, N-aryl (meth) acrylamide, N, N-dialkyl (meth) acrylamide, and N, N-diaryl (meth) acrylamide (meta) ) Acrylamide compounds.

Moreover, it is preferable that (meth) acrylic-type resin contains the carboxyl group contained in the unit derived from (meth) acrylic acid as an acidic group. In this case, the acid value of the (meth) acrylic resin and the SP _t can be adjusted by increasing or decreasing the amount of (meth) acrylic acid used when preparing the (meth) acrylic resin.

  When the (meth) acrylic resin is a resin obtained by copolymerizing other monomers other than the (meth) acrylic monomer, the other monomers include ethylene, propylene, butene-1, pentene-1, hexene-1, Olefins such as heptene-1 and octene-1; allyl esters such as allyl acetate, allyl benzoate, allyl acetoacetate, and allyl lactate; hexyl vinyl ether, octyl vinyl ether, ethylhexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl Vinyl ether, chloroethyl vinyl ether, 2-ethylbutyl vinyl ether, dimethylaminoethyl vinyl ether, diethylaminoethyl vinyl ether, benzyl vinyl ether, vinyl phenyl ether, vinyl tolyl ether, vinyl Vinyl ethers such as rolphenyl ether, vinyl-2,4-dichlorophenyl ether, and vinyl naphthyl ether; vinyl acetate, vinyl propionate, vinyl butyrate, vinyl isobutyrate, vinyl diethyl acetate, vinyl chloroacetate, vinyl Examples include vinyl esters such as methoxyacetate, vinylbutoxyacetate, vinylphenylacetate, vinylacetoacetate, vinyl lactate, vinyl benzoate, vinyl salicylate, vinyl chlorobenzoate, and vinyl naphthoate.

  Further, the (meth) acrylic resin may be one in which a chargeable functional group such as a quaternary ammonium salt is introduced, as in the case of the resin that can be used as the charge control agent.

  The total content of the units derived from the (meth) acrylic monomer contained in the (meth) acrylic resin is not particularly limited as long as the object of the present invention is not impaired, but is preferably 80% by mass or more, and 90% by mass. % Or more is more preferable, and 100 mass% or more is particularly preferable.

(Styrene- (meth) acrylic resin)
When a styrene- (meth) acrylic resin is used as the resin constituting the inner layer, the styrene- (meth) acrylic resin is a copolymer of at least a monomer containing a styrene monomer and a (meth) acrylic monomer. This is a resin obtained.

  Examples of the styrenic monomer used for the preparation of the styrene- (meth) acrylic resin include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-ethylstyrene, Examples include 2,4-dimethylstyrene, pn-butylstyrene, p-dodecylstyrene, p-methoxystyrene, p-phenylstyrene, and p-chlorostyrene.

  The (meth) acrylic monomer used for the preparation of the styrene- (meth) acrylic resin is the same as the (meth) acrylic monomer used for the preparation of the (meth) acrylic resin. Moreover, it is preferable that styrene- (meth) acrylic-type resin contains the carboxyl group contained in the unit derived from (meth) acrylic acid as an acidic group.

  In the case where the styrene- (meth) acrylic resin is a resin obtained by copolymerizing a styrene monomer and another monomer other than the (meth) acrylic monomer, examples of the other monomer are those in the (meth) acrylic resin. The same as other monomers other than the (meth) acrylic monomer.

  The total content of the units derived from the styrene monomer and the unit derived from the (meth) acrylic monomer contained in the styrene- (meth) acrylic resin is not particularly limited as long as the object of the present invention is not impaired. However, 80 mass% or more is preferable, 90 mass% or more is more preferable, and 100 mass% or more is especially preferable.

  In addition, the styrene- (meth) acrylic resin may be one in which a chargeable functional group such as a quaternary ammonium salt is introduced, as in the case of the resin that can be used as the charge control agent.

  The melting point (Tm) of the resin constituting the inner layer is preferably 80 ° C. or higher and 120 ° C. or lower, more preferably 85 ° C. or higher and 110 ° C. or lower, and more preferably 90 ° C. or higher and 100 ° C. or lower. If the melting point of the resin constituting the inner layer is too high, it may be difficult to fix the toner satisfactorily at a low temperature. If the melting point of the resin constituting the inner layer is too low, the heat resistant storage stability of the toner may be impaired. The melting point of the resin constituting the inner layer can be measured by the same method as the method for measuring the softening point of the binder resin.

The Tg of the resin constituting the inner layer is preferably 45 ° C. or higher and 60 ° C. or lower, and more preferably 50 ° C. or higher and 55 ° C. or lower. If the Tg of the resin constituting the inner layer is too low, toner particles may aggregate in a high temperature and high humidity environment. Further, if the Tg of the resin constituting the inner layer is too high, it may be difficult to fix the toner satisfactorily at a low temperature. The glass transition point of the resin constituting the inner layer can be measured by a method similar to the method for measuring the glass transition point of the binder resin.

  The number average molecular weight (Mn) of the resin constituting the inner layer is preferably 1,000 or more and 4,000 or less, and more preferably 1,500 or more and 3,000 or less. Further, the number average molecular weight (Mw) of the resin constituting the inner layer is preferably 1,500 or more and 11,000 or less, and more preferably 3,500 or more and 7,000 or less. Further, the molecular weight distribution (Mw / Mn) represented by the ratio of the number average molecular weight (Mn) to the mass average molecular weight (Mw) is preferably 2 or more and 10 or less. The number average molecular weight (Mn) and the mass average molecular weight (Mw) of the resin constituting the inner layer can be measured using gel permeation chromatography.

SP _t that is the SP value of the material of the inner layer is not particularly limited as long as SP _c , SP _t , and SP _s satisfy the above-described predetermined relationship, but is preferably 9.5 or more and 11.5 or less. By setting SP _t to a value within such a range, ΔSP ₁ can be easily adjusted to 0.3 or more and 1.4 or less, and ΔSP ₂ can be easily adjusted to 0.5 or more and 1.6 or less. In addition, by setting SP _t within such a range, the toner core particles and the inner layer of the shell layer are easily adhered to each other, and the inner layer and the outer layer of the shell layer are easily adhered to each other. It is easy to obtain toner with excellent strength.

  The mass of the inner layer is not particularly limited as long as the object of the present invention is not impaired. Specifically, the amount is preferably 10 parts by mass or more and 35 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the toner core particles.

[Outer layer]
The material of the outer layer is not particularly limited as long as SP _c , SP _t , and SP _s satisfy the predetermined relationship described above. The material of the outer layer, since it is easy to adjust the SP _s, (meth) acrylic resin, a styrene - (meth) acrylic resin, and one or more resins that are selected from the group consisting of polyester resins are preferred. And since it is easy to obtain the toner excellent in heat-resistant storage stability, the material of the outer layer is more preferably at least one resin selected from the group consisting of (meth) acrylic resins and styrene- (meth) acrylic resins. As the polyester resin suitably used as the resin constituting the outer layer, the same type of resin as the binder resin can be used. Moreover, the resin similar to the resin which comprises an inner layer can be used for the (meth) acrylic-type resin and styrene- (meth) acrylic-type resin suitably used as resin which comprises an outer layer.

  The melting point of the resin constituting the outer layer is preferably 95 ° C. or higher and 140 ° C. or lower, more preferably 100 ° C. or higher and 130 ° C. or lower, and more preferably 105 ° C. or higher and 125 ° C. or lower. If the melting point of the resin constituting the outer layer is too high, it may be difficult to fix the toner well at a low temperature. If the melting point of the resin constituting the outer layer is too low, the heat resistant storage stability of the toner may be impaired. The melting point of the resin constituting the outer layer can be measured by the same method as the method for measuring the softening point of the binder resin.

  The Tg of the resin constituting the outer layer is preferably 45 ° C. or higher and 80 ° C. or lower, more preferably 60 ° C. or higher and 70 ° C. or lower, and particularly preferably 63 ° C. or higher and 68.5 ° C. or lower. If the Tg of the resin constituting the outer layer is too low, toner particles may aggregate in a high temperature and high humidity environment. If the Tg of the resin constituting the outer layer is too high, it may be difficult to fix the toner well at a low temperature. The glass transition point of the resin constituting the outer layer can be measured by the same method as the method for measuring the glass transition point of the binder resin.

  The number average molecular weight (Mn) of the resin constituting the outer layer is preferably from 3,000 to 1,000,000, more preferably from 4,500 to 500,000. Further, the molecular weight distribution (Mw / Mn) represented by the ratio of the number average molecular weight (Mn) to the mass average molecular weight (Mw) is preferably 2 or more and 30 or less, and more preferably 3 or more and 10 or less. The number average molecular weight (Mn) and the mass average molecular weight (Mw) of the resin constituting the shell layer can be measured using gel permeation chromatography.

SP _s which is the SP value of the material of the outer layer is not particularly limited as long as SP _c , SP _t , and SP _s satisfy the above-described predetermined relationship, but is preferably 8.0 or more and 10.0 or less. By setting SP _s to a value within such a range, ΔSP ₂ can be easily adjusted to 0.5 or more and 1.6 or less, and the inner layer and the outer layer of the shell layer can be easily adhered to each other. For this reason, by setting SP _s to a value within such a range, it is easy to obtain a toner having excellent mechanical strength.

  The mass of the outer layer is preferably 15 parts by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the binder resin contained in the toner core particles.

[External additive]
The surface of the toner of the present invention may be treated with an external additive as desired. In the specification of the present application, particles treated with an external additive are referred to as “toner mother particles”. The type of external additive can be appropriately selected from external additives conventionally used for toners. Specific examples of suitable external additives include silica and metal oxides such as alumina, titanium oxide, magnesium oxide, zinc oxide, strontium titanate, and barium titanate. These external additives can be used in combination of two or more. Further, these external additives can be used after being hydrophobized using a hydrophobizing agent such as an aminosilane coupling agent or silicone oil. In the case of using a hydrophobized external additive, it is easy to suppress a decrease in charge amount of the toner under high temperature and high humidity, and it is easy to obtain a toner excellent in fluidity.

  The particle diameter of the external additive is preferably 0.01 μm or more and 1.0 μm or less.

  Typically, the amount of the external additive used is preferably 0.1 parts by mass or more and 10 parts by mass or less, and more preferably 0.2 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the toner base particles.

[Career]
The toner of the present invention can be mixed with a desired carrier and used as a two-component developer. When preparing a two-component developer, it is preferable to use a magnetic carrier.

  Suitable carriers when the toner of the present invention is used as a two-component developer include those in which a carrier core material is coated with a resin. Specific examples of the carrier core material include particles such as iron, oxidized iron, reduced iron, magnetite, copper, silicon steel, ferrite, nickel, and cobalt, and particles of alloys of these materials with manganese, zinc, and aluminum. , Particles like iron-nickel alloy, iron-cobalt alloy, titanium oxide, aluminum oxide, copper oxide, magnesium oxide, lead oxide, zirconium oxide, silicon carbide, magnesium titanate, barium titanate, lithium titanate, titanate Ceramic particles such as lead, lead zirconate and lithium niobate, particles of high dielectric constant materials such as ammonium dihydrogen phosphate, potassium dihydrogen phosphate and Rochelle salt, and the above magnetic particles dispersed in resin A resin carrier is mentioned.

  Specific examples of the resin covering the carrier core material include (meth) acrylic polymer, styrene polymer, styrene- (meth) acrylic copolymer, olefin polymer (polyethylene, chlorinated polyethylene, polypropylene). , Polyvinyl chloride, polyvinyl acetate, polycarbonate, cellulose resin, polyester resin, unsaturated polyester resin, polyamide resin, polyurethane resin, epoxy resin, silicone resin, fluororesin (polytetrafluoroethylene, polychlorotrifluoroethylene, polyfluoride) Vinylidene), phenol resin, xylene resin, diallyl phthalate resin, polyacetal resin, and amino resin. These resins can be used in combination of two or more.

  The particle diameter of the carrier is a particle diameter measured using an electron microscope, preferably 20 μm or more and 120 μm or less, and more preferably 25 μm or more and 80 μm or less.

  When the toner of the present invention is used as a two-component developer, the content of the toner in the two-component developer is preferably 3% by mass or more and 20% by mass or less, and preferably 5% by mass or more with respect to the mass of the two-component developer. 15 mass% or less is more preferable. By setting the toner content in the two-component developer within such a range, it is easy to maintain the image density of the formed image at an appropriate level, and image formation caused by suppression of toner scattering from the developing device Contamination inside the apparatus and toner adhesion to transfer paper can be suppressed.

[Method for producing toner for developing electrostatic image]
As a method for producing the toner of the present invention, an aggregation method is preferred because it is easy to obtain toner particles having a uniform shape and a shell layer having a uniform thickness is easily formed on the surface of the toner core particles. Hereinafter, a method for producing a toner for developing an electrostatic image using the aggregation method will be described.

The specific method of the aggregation method is not particularly limited, and various methods conventionally used as a toner production method can be applied. A suitable method for producing an electrostatic charge image developing toner using the aggregation method will be described in order by dividing it into the following steps (I) to (VI).
Step (I): After obtaining an aqueous medium dispersion (A) of fine particles containing a binder resin, the fine particles are aggregated in the presence of an aggregating agent to obtain an aqueous medium dispersion (B) containing toner core particles. Process,
Step (II): Mixing the aqueous medium dispersion (B) and the fine particle aqueous medium dispersion (C) containing a resin constituting the inner layer of the shell layer to form the toner core particles and the inner layer of the shell layer Obtaining an aqueous medium dispersion (D) containing fine particles containing a resin
Step (III): The aqueous medium dispersion (E) containing the toner core particles having the coating layer I composed of fine particles containing the resin constituting the inner layer of the shell layer by heating the aqueous medium dispersion (D). Obtaining step,
Step (IV): Toner core particles comprising a coating layer I on the surface by mixing an aqueous medium dispersion (E) and an aqueous medium dispersion (F) of fine particles containing a resin constituting the outer layer of the shell layer; Obtaining an aqueous medium dispersion (G) containing fine particles containing a resin constituting the outer layer of the shell layer;
Step (V): The aqueous medium dispersion liquid (G) is heated to form a coating layer I and a coating layer II comprising fine particles containing a resin constituting the outer layer of the shell layer and coating the outer surface of the coating layer I; Obtaining an aqueous medium dispersion liquid (H) containing toner core particles provided on the surface thereof,
Step (VI): A step of heating the aqueous medium dispersion (H) to form a shell layer composed of an inner layer and an outer layer on the surface of the toner core particles.
including.

The method for producing a toner for developing an electrostatic latent image of the present invention may include the following steps (VII) to (IX) as necessary, in addition to the steps (I) to (VI).
(VII): A cleaning step for cleaning the toner.
(VIII): A drying step of drying the toner.
(IX): an external addition step of attaching an external additive to the surface of the toner base particles.

  Hereinafter, steps (I) to (IX) will be described in order.

[Step (I)]
In step (I), after obtaining an aqueous medium dispersion (A) of fine particles containing a binder resin, the fine particles are aggregated in the presence of an aggregating agent to obtain an aqueous medium dispersion (B) containing toner core particles. obtain. Hereinafter, a method for preparing an aqueous medium dispersion (A) of fine particles containing a binder resin and a method for aggregating the fine particles will be described.

<Method for Preparing Aqueous Medium Dispersion (A) of Fine Particles Containing Binder>
The method for preparing the fine particle aqueous medium dispersion (A) containing the binder resin is not particularly limited. The fine particles containing the binder resin are either fine particles of the binder resin or fine particles of the binder resin composition containing the binder resin and optional components such as a colorant, a release agent, and a charge control agent. There may be. Usually, the fine particles containing a binder resin are fine particles having a desired size in an aqueous medium and containing a binder resin or a composition containing a binder resin and optional components such as a colorant, a release agent, and a charge control agent. By preparing, an aqueous medium dispersion of fine particles is prepared.

  Further, the aqueous medium dispersion liquid (A) of fine particles containing the binder resin may contain fine particles other than the fine particles containing the binder resin. Examples of the fine particles other than the fine particles containing the binder resin include release agent fine particles and colorant fine particles. Hereinafter, a method for preparing fine particles including a binder resin, a method for preparing fine particles of a release agent, a method for preparing fine particles of a colorant, and a method of preparing fine particles including a binder resin and a release agent will be described in order. In addition, about the microparticles | fine-particles containing a component different from the microparticles | fine-particles demonstrated here, it can prepare using the method suitably selected from the manufacturing method of these microparticles | fine-particles.

(Method for preparing fine particles containing binder resin)
Hereinafter, a preferred example of the method for preparing the binder resin fine particles will be described.

  First, the binder resin is heated to a temperature equal to or higher than its melting point to obtain a binder resin melt. The temperature at which the binder resin is melted is not particularly limited as long as the binder resin is uniformly melted, but a temperature of the melting point of the binder resin + 10 ° C. to the melting point + 30 ° C. is preferable.

  When a polyester resin is used as the binder resin, a basic substance may be added to the molten binder resin in order to neutralize the acid groups contained in the polyester resin. The basic substance is not particularly limited as long as it can neutralize acid groups contained in the polyester resin and does not impair the object of the present invention. Suitable basic materials include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, alkali metal carbonates such as sodium carbonate, and potassium carbonate, sodium bicarbonate, and hydrogen carbonate. Alkali metal hydrogen carbonate such as potassium, N, N-dimethylethanolamine, N, N-diethylethanolamine, triethanolamine, tripropanolamine, tributanolamine, triethylamine, n-propylamine, n-butylamine, isopropyl Examples thereof include nitrogen-containing organic bases such as amine, monomethanolamine, morpholine, methoxypropylamine, pyridine, and vinylpyridine. These basic compounds may be used individually by 1 type, and may be used in combination of 2 or more types.

  The amount of the basic compound used is appropriately determined in consideration of the acid value of the polyester resin. Typically, the amount of the basic compound used is preferably 1 part by mass or more and 20 parts by mass or less, and more preferably 5 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the binder resin.

  Further, a surfactant can be added to the binder resin melt. When a surfactant is added to the binder resin melt, fine particles of the binder resin can be stably dispersed in an aqueous medium.

  The surfactant that can be added to the binder resin melt is not particularly limited, and can be appropriately selected from the group consisting of an anionic surfactant, a cationic surfactant, and a nonionic surfactant. Examples of anionic surfactants include sulfate ester type surfactants, sulfonate type surfactants, phosphate ester type surfactants, and soaps. Examples of the cationic surfactant include an amine salt type activator and a quaternary ammonium salt type activator. Examples of nonionic surfactants include polyethylene glycol type activators, alkylphenol ethylene oxide adduct type activators, and polyhydric alcohol type activators that are derivatives of polyhydric alcohols such as glycerin, sorbitol, and sorbitan. . Among these surfactants, it is preferable to use at least one of an anionic surfactant and a nonionic surfactant. These surfactants may be used alone or in combination of two or more.

  As for the usage-amount of surfactant, 1 mass% or more and 10 mass% or less are preferable with respect to the mass of binder resin.

  An aqueous medium dispersion containing fine particles of the binder resin can be prepared by adding water to the binder resin melt thus prepared and further stirring and mixing. As a device for stirring the binder resin melt and water, a stirring device having a function of maintaining the temperature of the contents is preferable in order to hold the binder resin in a molten state. As a suitable method for maintaining the temperature of the contents in the stirring device, there is a method of using a stirring device equipped with a jacket and circulating hot water, water vapor, or heat medium oil at a predetermined temperature in the jacket. As a specific example of a suitable stirring apparatus, a heating kneading apparatus (TK Hibis Disper Mix HM-3D-5 (manufactured by PRIMIX Corporation)) may be mentioned.

The particle diameter of the fine particles of the binder resin contained in the aqueous medium dispersion containing the fine particles of the binder resin obtained by stirring the melt of the binder resin and water is the same as that of the binder resin melt and water. It can adjust by adjusting the stirring speed at the time of mixing. The volume average particle diameter (D ₅₀ ) of the fine particles of the binder resin is preferably 1 μm or less, and more preferably 0.05 μm or more and 0.5 μm or less. When the particle size of the fine particles of the binder resin is in such a range, the particle size distribution is sharp and it is easy to obtain a toner having a uniform shape, so that variations in toner performance and productivity are reduced. The volume average particle size (D ₅₀ ) of the fine particles of the binder resin can be measured using a laser diffraction / scattering particle size distribution measuring device (LA-950 (manufactured by Horiba, Ltd.)).

(Preparation of fine particles containing release agent)
Hereinafter, a suitable example of the method for preparing the release agent fine particles will be described. The method for preparing the release agent fine particles is not limited to the method described below.

  First, the release agent is pulverized to about 100 μm or less in advance to obtain a release agent powder. A release agent powder is added to an aqueous medium containing a surfactant to prepare a slurry. The resulting slurry is then heated to a temperature above the melting point of the release agent. A strong shearing force is applied to the heated slurry using a homogenizer or a pressure discharge type disperser to prepare an aqueous dispersion containing release agent fine particles.

  As a device for applying a strong shearing force to the dispersion, NANO3000 (manufactured by Miki Co., Ltd.), nanomizer (manufactured by Yoshida Kikai Kogyo Co., Ltd.), micro full dizer (manufactured by MFI), gorin homogenizer (manufactured by Manton Gorin), and Clare mix W motion (M Technique Co., Ltd.) is listed.

The volume average particle diameter (D ₅₀ ) of the release agent fine particles contained in the aqueous medium dispersion containing the release agent fine particles is preferably 1 μm or less, and more preferably 0.1 μm or more and 0.7 μm or less. When fine particles of a release agent having a particle diameter in such a range are used, it is easy to obtain a toner in which the release agent is uniformly dispersed in the binder resin. The volume average particle size of the fine particles of the release agent (D ₅₀₎ can be measured in the same manner as the volume average particle diameter of the binder resin (D _50).

(Preparation of fine particles containing colorant)
Hereinafter, a suitable example of a method for preparing fine particles of a colorant will be described. The method for preparing the fine particles of the colorant is not limited to the method described below.

  In an aqueous medium containing a surfactant, a colorant and, if necessary, a component such as a colorant dispersant are dispersed using a known disperser to obtain fine particles containing the colorant. . The type of the surfactant is not particularly limited, and any of an anionic surfactant, a cationic surfactant, and a nonionic surfactant can be used. The amount of the surfactant used is not particularly limited, but is preferably not less than the critical micelle concentration (CMC).

  Dispersers used for dispersion treatment are not particularly limited, and pressure dispersers such as ultrasonic dispersers, mechanical homogenizers, manton gourins, and pressure homogenizers, sand grinders, horizontal and vertical bead mills, and ultra apex mills. Media type dispersers such as (manufactured by Kotobuki Kogyo Co., Ltd.), dyno mill (manufactured by WAB Co., Ltd.), MSC mill (manufactured by Nippon Coke Kogyo Co., Ltd.) can be used.

The volume average particle diameter (D ₅₀ ) of the fine particles of the colorant is preferably 0.05 μm or more and 0.2 μm or less.

(Preparation method of fine particles containing binder resin and release agent)
Hereinafter, a preferred example of a method for preparing fine particles containing a binder resin and a release agent will be described.

  The fine particles containing the binder resin and the release agent are the same as those described above except that the release resin is contained in the binder resin melt with respect to the preferred method for preparing the fine particles of the binder resin. It can be prepared using a method similar to the preferred method for preparing the fine particles of the resin.

  As a preferred method of incorporating a release agent into the binder resin melt, (a) a method of melting the resulting mixture after mixing the solid state binder resin and the release agent, and (b) release. After the mold is heated and melted, the binder resin is added to the melted release agent and both are melted by heating; and (c) the binder resin is heated and melted and then melted An example is a method in which a release agent is added to the binder resin and both are heated and melted.

  In addition, although the preparation method of microparticles | fine-particles containing binder resin and a mold release agent was demonstrated as mentioned above, the microparticles | fine-particles containing binder resin, a coloring agent, and a mold release agent also change the component mix | blended with binder resin. Other than that, it can be prepared in the same manner as described above.

<Agglomeration method of fine particles>
The fine particles prepared by using the above method are combined as appropriate so that a predetermined component is contained in the toner to form toner core particles that are fine particle aggregates. A suitable method for aggregating the fine particles includes a method of adding an aggregating agent to the aqueous dispersion of fine particles.

  Examples of the flocculant include inorganic metal salts, inorganic ammonium salts, and divalent or higher metal complexes. Inorganic metal salts include metal salts such as sodium sulfate, sodium chloride, calcium chloride, calcium nitrate, barium chloride, magnesium chloride, zinc chloride, aluminum chloride, and aluminum sulfate; inorganics such as polyaluminum chloride and polyaluminum hydroxide A metal salt polymer is mentioned. Examples of inorganic ammonium salts include ammonium sulfate, ammonium chloride, and ammonium nitrate. Further, a quaternary ammonium salt type cationic surfactant, polyethyleneimine can also be used as a flocculant.

  As the flocculant, a divalent metal salt and a monovalent metal salt are preferably used. A divalent metal salt and a monovalent metal salt are preferably used in combination. Since the divalent metal salt and the monovalent metal salt have different aggregation speeds of the fine particles, when used together, the particle diameter of the obtained toner core particles is controlled and the particle size distribution is easily sharpened.

  The addition amount of the flocculant is preferably 0.1 mmol / g or more and 10 mmol / g or less with respect to the solid content of the aqueous medium dispersion containing fine particles. Moreover, it is preferable to adjust suitably the addition amount of a flocculant according to the kind and quantity of surfactant which are contained in the aqueous medium dispersion liquid containing microparticles | fine-particles.

  The conditions for adding the aggregating agent are not particularly limited as long as the aggregation of the fine particles proceeds well. The flocculant is preferably added at a temperature not higher than the glass transition point of the binder resin after adjusting the pH of the aqueous medium dispersion containing fine particles. When a polyester resin is used as the binder resin for the toner, it is preferable to add the flocculant after adjusting the pH of the aqueous medium dispersion containing fine particles to the alkali side, preferably pH 10 or higher. When such a method is used, uniform agglomeration can be performed and the particle size distribution of the toner core particles can be sharpened. The flocculant may be added at one time or may be added sequentially.

  After aggregation has progressed until the toner core particles, which are fine particle aggregates, have a desired particle size, it is preferable to add an aggregation terminator. Examples of the aggregation terminator include sodium chloride and sodium hydroxide. In this way, an aqueous medium dispersion (B) containing toner core particles can be obtained.

[Step (II)]
In the step (II), the aqueous medium dispersion (B) obtained in the step (I) and the aqueous medium dispersion (C) containing fine particles containing a resin constituting the inner layer of the shell layer are mixed to form a toner core. An aqueous medium dispersion (D) containing particles and fine particles containing a resin constituting the inner layer of the shell layer is obtained. The method for mixing the aqueous medium dispersion (B) and the aqueous medium dispersion (C) is not particularly limited as long as the object of the present invention is not impaired. Hereinafter, a preferred method for preparing the fine particle aqueous medium dispersion (C) containing the resin constituting the inner layer of the shell layer will be described.

<Preparation of aqueous medium dispersion (C) of fine particles containing resin constituting inner layer of shell layer>
The fine particle aqueous medium dispersion (C) containing a resin constituting the inner layer of the shell layer is prepared by a suitable method according to the type of the resin constituting the inner layer of the shell layer. When a polyester resin is used as the resin constituting the inner layer of the shell layer, the fine particles containing the resin constituting the inner layer of the shell layer are prepared by the same method as the method for preparing the fine particles containing the binder resin described above. Is preferred. Further, as a resin constituting the inner layer of the shell layer, a carboxyl group-containing vinyl polymer such as a (meth) acrylic resin containing a unit derived from (meth) acrylic acid and a styrene- (meth) acrylic resin is also used. Preferably used. In the specification of the present application, a homopolymer or copolymer of a compound having a vinyl group such as ethylene, propylene, (meth) acrylic acid, (meth) acrylic acid ester, and styrene is referred to as a vinyl polymer. Hereinafter, a method for preparing the aqueous medium dispersion (C) when a carboxyl group-containing vinyl polymer is used as the resin constituting the inner layer of the shell layer will be described.

(Method for preparing fine particles containing carboxyl group-containing vinyl polymer)
When a carboxyl group-containing vinyl polymer such as (meth) acrylic resin and styrene- (meth) acrylic resin is used as the resin constituting the inner layer of the shell layer, the resin constituting the inner layer of the shell layer is included. A fine particle aqueous medium dispersion (C) is prepared in a sealable reaction vessel equipped with a stirrer, a thermometer, and a heater, an aqueous medium, a pulverized product of a carboxyl group-containing vinyl polymer, a neutralizer, and an organic solvent Is obtained by stirring and mixing under heating.

  When two or more types of carboxyl group-containing vinyl polymers are used, a mixture of two or more different types of carboxyl group-containing vinyl polymers may be used as the pulverized product. A pulverized product obtained by pulverizing melt-kneaded products of different types of carboxyl group-containing vinyl polymers may be used.

  Examples of neutralizing agents used when a carboxyl group-containing vinyl polymer is used as the resin constituting the inner layer of the shell layer include alkali metal compounds such as sodium hydroxide and potassium hydroxide, ammonia, Dimethylamine, trimethylamine, monoethylamine, diethylamine, triethylamine, N, N-dimethylethanolamine, aminoethanolamine, N-methyl-N, N-diethanolamine, isopropylamine, iminobispropylamine, 3-ethoxypropylamine, 3- Existence such as diethylaminopropylamine, sec-butylamine, propylamine, methylaminopropylamine, 3-methoxypropylamine, monoethanolamine, morpholine, N-methylmorpholine, N-ethylmorpholine Amine compounds. Among these, it is preferable to use diethylamine or triethylamine as a neutralizing agent. Moreover, the neutralizing agent may be used alone or in combination of two or more.

  The boiling point of the neutralizing agent used for the preparation of the aqueous medium dispersion (C) is preferably 0 ° C. or higher and 250 ° C. or lower. If the boiling point is too low, the neutralizing agent tends to volatilize from the aqueous medium dispersion (C), and the dispersibility of the fine particles containing the carboxyl group-containing vinyl polymer in the aqueous medium may be impaired. On the other hand, if the boiling point of the neutralizing agent is too high, the neutralizing agent tends to remain in the toner, and the heat resistant storage stability of the toner may be impaired.

  The amount of the neutralizing agent used for the preparation of the aqueous medium dispersion (C) is preferably 0.5 to 15 molar equivalents relative to the number of carboxyl groups contained in the carboxyl group-containing vinyl polymer. The molar ratio is more preferably from 8 molar equivalents to 3.0 molar equivalents, particularly preferably from 1.0 molar equivalents to 2.5 molar equivalents.

  When an organic amine compound and / or ammonia is used as the neutralizing agent, solvent removal treatment is performed on the aqueous medium dispersion liquid (C) of fine particles containing a carboxyl group-containing vinyl polymer, whereby the aqueous medium dispersion liquid (C) At least a part of the organic amine compound and / or ammonia can be distilled off. Also in this case, the amount of the organic amine compound and / or ammonia remaining in the aqueous medium dispersion (C) is 0.5 molar equivalent or more with respect to the number of moles of the carboxyl group contained in the carboxyl group-containing vinyl polymer. preferable. When the aqueous medium dispersion (C) thus prepared is used, a toner having good heat-resistant storage stability can be easily obtained. The content of the organic amine compound and / or ammonia in the toner can be quantified by gas chromatography.

  The organic solvent used for preparing the aqueous medium dispersion (C) of fine particles containing a carboxyl group-containing vinyl polymer is used for the purpose of improving the dispersibility of the fine particles containing a carboxyl group-containing vinyl polymer. Examples of the organic solvent include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, tert-butanol, n-amyl alcohol, isoamyl alcohol, sec-amyl alcohol, tert-amyl alcohol, Alcohols such as 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol, cyclohexanol; ketones such as methyl ethyl ketone, methyl isobutyl ketone, ethyl butyl ketone, cyclohexanone, isophorone; tetrahydrofuran, dioxane Ethers such as: ethyl acetate, acetic acid-n-propyl, isopropyl acetate, acetic acid-n-butyl, isobutyl acetate, acetic acid-sec-butyl, acetic acid-3-methoxybutyl, Esters such as methyl lopionate, ethyl propionate, diethyl carbonate, dimethyl carbonate; ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol ethyl ether acetate, Glycols or glycols such as diethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol ethyl ether acetate, propylene glycol, propylene glycol monomethyl ether, propylene glycol monobutyl ether, propylene glycol methyl ether acetate Lumpur derivatives; 3-methoxy-3-methylbutanol; 3-methoxy butanol; acetonitrile; dimethylformamide; dimethylacetamide; diacetone alcohol; ethyl acetoacetate and the like. Among these, it is preferable to use one or more selected from methanol, ethanol, n-propanol, and isopropanol as the organic solvent in terms of easy removal from the aqueous medium dispersion (C). Two or more organic solvents may be used in combination.

  The solubility of the organic solvent used for the preparation of the aqueous medium dispersion (C) in 1 liter of water at 20 ° C. is preferably 50 g / liter or more, more preferably 100 g / liter or more. The boiling point of the organic solvent is preferably 30 ° C. or higher and 250 ° C. or lower, and more preferably 50 ° C. or higher and 200 ° C. or lower.

  By using an organic solvent having such physical properties, fine particles containing a carboxyl group-containing vinyl polymer can be favorably dispersed in an aqueous medium.

  The molecular weight of the organic solvent used for the preparation of the aqueous medium dispersion (C) is not particularly limited as long as the object of the present invention is not impaired, but a molecular weight of 90 or less is preferable. If the molecular weight is too large, the dispersibility of the fine particles containing a carboxyl group-containing vinyl polymer in an aqueous medium may be impaired.

  The amount of the organic solvent used for the preparation of the aqueous medium dispersion (C) is preferably 5% by mass or more and 50% by mass or less with respect to the mass of the carboxyl group-containing vinyl polymer.

  The volume average particle diameter of the fine particles containing the resin constituting the inner layer of the shell layer is preferably 0.03 μm or more and 0.50 μm or less, and more preferably 0.05 μm or more and 0.30 μm or less. When the fine particles containing the resin constituting the inner layer of the shell layer have a volume average particle diameter in such a range, the coating layer I composed of the fine particles of the resin constituting the inner layer of the shell layer is uniformly applied to the surface of the toner core particles. Easy to form. The volume average particle diameter of the fine particles containing the resin constituting the inner layer of the shell layer can be measured using, for example, an electrophoretic light scattering photometer (LA-950V2 (manufactured by Horiba, Ltd.)).

  In order to stabilize the dispersion state of the fine particles in the dispersion before mixing the aqueous medium dispersion (B) and the aqueous medium dispersion (C), a basic substance is added to the aqueous medium dispersion (C) in advance. To adjust the pH of the aqueous medium dispersion (C) to about 8.

[Step (III)]
In the step (III), the aqueous medium dispersion (D) obtained in the step (II) is heated to include toner core particles provided with a coating layer I composed of fine particles including a resin constituting the inner layer of the shell layer on the surface thereof. An aqueous medium dispersion (E) is obtained. The temperature for heating the aqueous medium dispersion (D) is preferably 50 ° C. or higher and 65 ° C. or lower. By heating the aqueous medium dispersion liquid (D) at a temperature within such a range, the coating layer I composed of fine particles containing a resin constituting the inner layer of the shell layer can be uniformly formed on the surface of the toner core particles. .

[Step (IV)]
In step (IV), the aqueous medium dispersion (E) obtained in step (III) and the aqueous medium dispersion (F) of fine particles containing a resin constituting the outer layer of the shell layer are mixed to coat the surface. An aqueous medium dispersion (G) containing toner core particles having the layer I and fine particles containing a resin constituting the outer layer of the shell layer is obtained. The method of mixing the aqueous medium dispersion (E) and the aqueous medium dispersion (F) is not particularly limited as long as the object of the present invention is not impaired. Further, as a method for preparing the fine particle aqueous medium dispersion liquid (F) containing the resin constituting the outer layer of the shell layer, the fine particle aqueous medium dispersion liquid (C) containing the resin constituting the inner layer of the shell layer described above is suitable. The same method as the preparation method.

  The volume average particle diameter of the fine particles containing the resin constituting the outer layer of the shell layer is preferably 0.03 μm or more and 0.50 μm or less, more preferably 0.05 μm or more and 0.30 μm or less. When the fine particles containing the resin constituting the outer layer of the shell layer have a volume average particle diameter in such a range, the coating layer II composed of the fine particles of the resin constituting the outer layer of the shell layer is uniformly formed on the outer surface of the coating layer I. Easy to form. The volume average particle diameter of the fine particles containing a resin constituting the outer layer of the shell layer can be measured using, for example, an electrophoretic light scattering photometer (LA-950V2 (manufactured by Horiba, Ltd.)).

  In order to stabilize the dispersion state of the fine particles in the dispersion before mixing the aqueous medium dispersion (E) and the aqueous medium dispersion (F), a basic substance is added to the aqueous medium dispersion (F) in advance. To adjust the pH of the aqueous medium dispersion (F) to about 8.

[Process (V)]
In the step (V), the aqueous medium dispersion (G) obtained in the step (IV) is heated to form a coating layer I and fine particles containing a resin constituting the outer layer of the shell layer, and the outer surface of the coating layer I And an aqueous medium dispersion (H) containing toner core particles. The temperature at which the aqueous medium dispersion (G) is heated is preferably 50 ° C. or higher and 85 ° C. or lower. By heating the aqueous medium dispersion (G) at a temperature within such a range, the coating layer II composed of resin fine particles constituting the outer layer of the shell layer can be uniformly formed on the outer surface of the coating layer I. it can.

[Process (VI)]
In the step (VI), the aqueous medium dispersion (H) obtained in the step (V) is heated to form a shell layer having an inner layer and an outer layer on the surface of the toner core particles. A medium dispersion is obtained. Before the aqueous medium dispersion (H) is heated, it is preferable to add the above-mentioned aggregation terminator to the aqueous medium dispersion (H) after the formation of the coating layer II has progressed to a desired degree. Examples of the aggregation terminator include sodium chloride and sodium hydroxide.

  The temperature at which the aqueous medium dispersion (H) is heated is preferably not less than the glass transition point (Tg) of the resin constituting the outer layer of the shell layer and not more than 90 ° C. By heating the aqueous medium dispersion (G) at a temperature within such a range, the coating layer I and the coating layer II can be favorably formed, and the toner core particles can be satisfactorily covered with the shell layer. it can.

[Process (VII)]
The toner particles or toner base particles obtained in the step (VI) are washed with water in the washing step (VII) as necessary. The washing method is not particularly limited, and the toner particles or toner base particles are recovered as a wet cake by solid-liquid separation from the aqueous medium dispersion containing toner particles or toner base particles, and the obtained wet cake is used with water. And a method of precipitating particles in an aqueous medium dispersion containing toner particles or toner base particles, replacing the supernatant with water, and redispersing the toner particles or toner base particles in water after the replacement. It is done.

[Process (VIII)]
The toner particles or toner base particles obtained in the step (VI) are dried through a drying step (VIII) as necessary. The method for drying the toner particles or toner base particles is not particularly limited. Suitable drying methods include methods using a dryer such as a spray dryer, fluidized bed dryer, vacuum freeze dryer, and vacuum dryer. Among these methods, a method using a spray dryer is more preferable because aggregation of toner particles during drying is easily suppressed. When the particles recovered in the step (VI) are used as toner base particles, a dispersion of an external additive such as silica is added to the toner base particles together with an aqueous medium dispersion containing the toner base particles using a spray dryer. By spraying, the external additive can be attached to the surface of the toner base particles.

[Step (IX)]
The electrostatic latent image developing toner produced using the method of the present invention may be one having an external additive attached to the surface thereof, if necessary. In step (IX), particles recovered through the above-described method steps are used as toner base particles, and an external additive is attached to the surface of the toner base particles. A method for attaching the external additive to the surface of the toner base particles is not particularly limited. As a suitable method, there is a method of mixing by using a mixer such as a Henschel mixer or a Nauter mixer, adjusting the conditions so that the external additive is not buried in the surface of the toner base particles.

  The toner for developing an electrostatic image of the present invention described above is well fixed on a recording medium in a wide temperature range, and is excellent in heat resistant storage stability and mechanical strength. Therefore, the electrostatic image developing toner of the present invention is preferably used in various image forming apparatuses.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not limited at all based on an Example.

[Preparation Example 1]
(Preparation of polyester resin fine particle dispersion)
A polyester resin fine particle dispersion was prepared according to the following method.
As a polyester resin used for the preparation of the polyester resin fine particle dispersion, a polyester resin having physical properties shown in Table 1 prepared by appropriately changing the blending ratio of the following monomers a to b was used.
Monomer a: Polyoxypropylene (2,2) -2,2-bis (4-hydroxyphenyl) propane monomer b: Polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) ) Propane monomer c: fumaric acid monomer d: trimellitic acid

  The polyester resin was pulverized using a pulverizer to obtain a polyester resin powder having an average particle diameter of about 30 μm. Next, 200 g of the obtained polyester resin powder, 30 g of a 1N-sodium hydroxide aqueous solution (concentration 4%), and 770 g of ion-exchanged water are mixed using a mixing device to obtain an aqueous suspension containing the polyester resin powder. It was.

  The aqueous suspension containing the obtained polyester resin powder was put into a 2 L round bottom stainless steel container equipped with a condenser and a stirring device (RW20 digital (manufactured by IKA)). Next, 1% by mass of an anionic surfactant (sodium lauryl sulfate, Emar 0 (manufactured by Kao Corporation)) was added to the stainless steel container with respect to the mass of the resin. Thereafter, the temperature of the aqueous suspension was raised to 95 ° C. The aqueous suspension was stirred for 30 minutes at the same temperature and a rotation speed of 200 rpm. Thereafter, the aqueous suspension rapidly cooled to room temperature was filtered using a # 300 mesh filter to obtain a wet cake of a low oligomer polyester resin. The low oligomer polyester resin was obtained by washing the wet cake of the low oligomer polyester resin with water and drying.

  The obtained low oligomer polyester resin powder was put into a heating kneading apparatus (TK Hibis Dispermix HM-3D-5 (manufactured by PRIMIX Corporation)) equipped with a temperature adjusting jacket. The low oligomer polyester resin powder was melted by heating to 120 ° C. while stirring the low oligomer polyester resin powder at a revolution of 20 rpm and a rotation of 48 rpm. Thereafter, 80 g of triethanolamine (basic compound) and 80 g of an aqueous solution having a concentration of 25% by mass of sodium lauryl sulfate (surfactant, EMAL 0 (manufactured by Kao Corporation)) were added to the melt. Next, the melt was stirred for 15 minutes at revolution 40 rpm and rotation 97 rpm. Thereafter, 2870 g of 98 ° C. ion-exchanged water was added to the melt at a rate of 50 g / min to obtain a resin emulsion. The emulsion was cooled to 50 ° C. at a rate of 5 ° C./min to obtain a polyester resin fine particle dispersion having a solid content of 25% by mass. The average particle diameter of the polyester resin fine particles in the dispersion was about 115 nm. The particle diameter of the polyester resin fine particles was measured using a particle diameter measuring device (LA-950 (manufactured by Horiba, Ltd.)).

[Preparation Example 2]
(Preparation of acrylic resin fine particle dispersion)
According to the following method, the amount of the polymerization initiator used, the blending ratio of the monomers, and the amount of the chain transfer agent are appropriately changed, and acrylic resin fine particle dispersions A to I having the physical property values shown in Table 2 are obtained. Prepared.
A 1000 ml four-necked flask equipped with a stirrer, a cooling tube, a nitrogen introduction tube, and a temperature sensor was charged with 550 ml of ion-exchanged water and 0.35 g of sodium dodecyl sulfate in the amount shown in Table 2 as a surfactant under a nitrogen stream. The mixture was heated to 80 ° C. with stirring at, and then an aqueous potassium persulfate solution (2.5% by mass concentration) was added as a polymerization initiator. A monomer mixture containing styrene, n-butyl acrylate and methacrylic acid, and n-octyl mercaptan as a chain transfer agent was dropped in a dropping funnel over 1.5 hours. After the dropping, the reaction solution was stirred at the same temperature for 2 hours to complete the polymerization reaction. After completion of the polymerization reaction, the content is cooled to room temperature, and then ion-exchanged water is added to the reaction solution so that the solid content concentration is 25% by mass, and the acrylic resin fine particle dispersion having the physical properties shown in Table 2 is added. Got. The average particle diameter of the acrylic resin fine particles in the dispersion was about 90 nm. The average particle diameter of the acrylic resin fine particles was measured using the same method as that for the polyester resin fine particles.

[Preparation Example 3]
(Method for preparing release agent fine particle dispersion)
200 g of release agent (ester wax, WEP-3 (manufactured by NOF Corporation)), 20 g of anionic surfactant (sodium lauryl sulfate, Emar 0 (manufactured by Kao Corporation)) and 780 g of ion-exchanged water are mixed. After heating to 90 ° C., emulsification was performed at a stirring speed of 2,000 rpm for 5 minutes using a homogenizer (Ultra Turrax T50 (manufactured by IKA)). Furthermore, using a high-pressure homogenizer (NV-200 (manufactured by Yoshida Kikai Kogyo Co., Ltd.), heating system added), emulsification is performed under the processing conditions of 100 ° C. and discharge pressure of 100 MPa, and the solid content concentration is 10% by mass. A mold fine particle dispersion was obtained. The average particle diameter of the release agent fine particles contained in the release agent fine particle dispersion was 120 nm. The particle size of the release agent fine particles was measured using the same method as that for the polyester resin fine particles.

[Preparation Example 4]
(Preparation method of pigment fine particle dispersion)
100 g of pigment (cyan pigment, CI pigment blue 15: 3 (copper phthalocyanine)), 20 g of sodium polyoxyethylene lauryl sulfate (Emar E27C (manufactured by Kao Corporation)) and 380 g of ion-exchanged water are mixed. Using an ultra apex mill (manufactured by Kotobuki Kogyo Co., Ltd.) with 400 ml of beads (made by zirconia, φ0.1) in a stirring vessel, dispersion treatment is performed under conditions of a rotor peripheral speed of 10 m / sec and a holding time of 2 hours. A pigment fine particle dispersion having a pigment concentration of 20% by mass and a total solid content of 21% by mass was obtained. The average particle diameter of the pigment fine particles contained in the pigment fine particle dispersion was 113 nm. The particle diameter of the pigment fine particles was measured using the same method as that for the polyester resin fine particles.

[Examples 1 to 4 and Comparative Examples 1 to 8]
[Toner base particle preparation process]
In a round bottom flask made of stainless steel having a capacity of 2 L, 340 g of a polyester resin fine particle dispersion of the types shown in Tables 3 to 5 as a binder resin, 100 g of a release agent fine particle dispersion, 25 g of a pigment dispersion, and ion-exchanged water 500 g was added and mixed at 25 ° C. Next, the mixture in the flask was stirred for 10 minutes at a rotation speed of 200 rpm using a stirring blade. The pH of the mixture in the flask was adjusted to 10 using an aqueous sodium hydroxide solution, and then the mixture was stirred for 10 minutes. Thereafter, 10 g of a magnesium chloride hexahydrate aqueous solution (flocculating agent) having a concentration of 50% by mass was dropped into the flask over 5 minutes. Next, the mixture in the flask was heated at a rate of 0.2 ° C./min to start agglomeration of fine particles. After the temperature increase was stopped at 50 ° C., the mixture in the flask was stirred at 300 rpm. While maintaining at 50 ° C. for 30 minutes, the aggregation of the fine particles was allowed to proceed. Thereafter, 50 g of an aqueous sodium chloride solution having a concentration of 20% by mass was added to the mixture in the flask to stop the progress of the aggregation of the fine particles to obtain a fine particle aggregate dispersion containing the fine particle aggregates.

  100 g of an aqueous solution of sodium lauryl sulfate (Emar 0 (manufactured by Kao Corporation)) having a concentration of 5% by mass was added to the fine particle aggregate dispersion in the flask. Next, the dispersion containing the fine particle aggregate was heated to 65 ° C. at a rate of 0.2 ° C./min while stirring at a stirring rate of 300 rpm. After raising the temperature to 65 ° C., the mixture was stirred at the same temperature for 1 hour at 300 rpm to unite the toner components contained in the fine particle aggregate and to control the shape of the fine particle aggregate to be spherical. Thereafter, the dispersion liquid containing fine particle aggregates was cooled to 25 ° C. at a rate of 10 ° C./min to obtain a toner core particle dispersion liquid containing fine particle aggregates whose shape was controlled as toner core particles.

  Next, 100 g of a polyester resin fine particle dispersion used as a material for the inner layer of the shell layer of the type shown in Tables 3 to 5 is adjusted to pH 8 using an aqueous sodium hydroxide solution, and then added to the toner core particle dispersion in the flask. did. Next, the contents of the flask were heated to 55 ° C. at a rate of 0.2 ° C./min while stirring at a stirring rate of 300 rpm. After the temperature was raised to 55 ° C., the mixture was stirred at the same temperature for 1 hour at 300 rpm to obtain a dispersion of toner core particles whose surface was coated with polyester resin fine particles.

  Next, 202 g of the acrylic resin fine particle dispersion 202 g used as the material of the outer layer of the shell layer of the types described in Tables 3 to 5 was adjusted to pH 8 using an aqueous sodium hydroxide solution, and then added to the dispersion in the flask. . The contents of the flask were heated to 60 ° C. at a rate of 0.2 ° C./min while stirring at a stirring rate of 300 rpm. After the temperature was raised to 60 ° C., stirring was performed at the same temperature for 2 hours under the condition of 300 rpm to obtain toner core particles in which the surface of the coating layer made of polyester resin fine particles was coated with acrylic resin fine particles.

  Next, an aqueous sodium chloride solution in which 71.5 g of sodium chloride was dissolved in 288 g of ion-exchanged water was added to the contents of the flask, and then the contents of the flask were stirred at a stirring speed of 360 rpm while adding 0.5 ° C. / The temperature was raised to 95 ° C. at a rate of minutes. After heating up to 95 degreeC, it stirred on the conditions of 360 rpm at the same temperature for 2 hours. Thereafter, the flask contents are cooled to 25 ° C. at a rate of 1 ° C./min, and after adjusting the pH of the flask contents to 2 using hydrochloric acid, a shell layer is formed on the surface of the toner core particles. A toner mother particle dispersion containing toner mother particles was obtained.

  The volume average particle diameter and sphericity of the toner base particles thus obtained were measured using a particle size distribution measuring device (Microtrack UPA150 (Nikkiso Co., Ltd.)). The volume average particle size of the toner base particles obtained in Examples 1 to 4 and Comparative Examples 1 to 8 was 5.5 μm, and the sphericity was about 0.98.

[Washing process]
Using a Buchner funnel, a wet cake of toner base particles was filtered from the toner base particle dispersion. The wet cake of toner base particles was again dispersed in ion exchange water to wash the toner. The same washing using the ion exchange water of the toner mother particles was repeated 6 times.

[Drying process]
A wet cake of toner base particles was dispersed in an aqueous ethanol solution having a concentration of 50% by mass to prepare a slurry. The obtained slurry was supplied to a continuous surface reformer (Coat Mizer (Freund Sangyo Co., Ltd.)), and the toner base particles in the slurry were dried to obtain toner base particles. Drying conditions using the coatizer were a hot air temperature of 45 ° C. and a blower air volume of 2 m ³ / min.

[External addition process]
The toner base particles obtained in each of Examples and Comparative Examples were subjected to external addition treatment.
Specifically, 100 parts by mass of toner base particles and 0.4 parts by mass of positively charged silica (silica 90G (manufactured by Nippon Aerosil Co., Ltd.): silica surface treated with silicone oil and aminosilane) Using a 5 L Henschel mixer (manufactured by Mitsui Miike Kogyo Co., Ltd.), the mixture was mixed for 5 minutes under the condition of a stirring speed of 30 m / sec to adhere the external additive. Thereafter, the toner was sieved using a sieve of 300 mesh (aperture 48 μm).

≪Evaluation≫
The toners of Examples 1 to 4 and Comparative Examples 1 to 8 were evaluated for fixability, heat resistance, and strength according to the following methods. The evaluation results of the fixability, heat resistance, and strength of the toners of Examples 1 to 4 and Comparative Examples 1 to 8 are shown in Tables 3 to 5.

A two-component developer used for evaluation of fixability was prepared according to the following method.
[Preparation of two-component developer]
(Preparation of carrier)
Each raw material is blended so as to be 39.7 mol% in terms of MnO, 9.9 mol% in terms of MgO, 49.6 mol% in terms of Fe ₂ O ₃ , and 0.8 mol% in terms of SrO, and then water is added to the wet ball mill. And pulverized and mixed for 10 hours. The resulting mixture was dried and then kept at 950 ° C. for 4 hours. Next, the mixture was pulverized with a wet ball mill for 24 hours to prepare a slurry. After granulating and drying the slurry, the granulated product was held at 1270 ° C. for 6 hours in an atmosphere with an oxygen concentration of 2%, and then crushed and adjusted in particle size to obtain manganese-based ferrite particles (carrier core material). . The obtained manganese-based ferrite particles had an average particle diameter of 35 μm and a saturation magnetization of 70 Am ² / kg when the applied magnetic field was 3000 (10 ³ / 4π · A / m).

  Next, a polyamideimide resin (copolymer of trimellitic anhydride and 4,4'-diaminodiphenylmethane) was diluted with methyl ethyl ketone to prepare a resin solution. Subsequently, tetrafluoroethylene / hexafluoropropylene copolymer (FEP) and silicon oxide (2% by mass of the total amount of the resin) are dispersed in the resin solution, and an amount of carrier coat liquid that is 150 g in terms of solid content. Got. The mass ratio of polyamideimide resin and FEP was 2/8 as polyamideimide resin / FEP, and the solid content ratio of the resin solution was 10 mass%.

  Using the obtained carrier coat solution, 10 kg of manganese-based ferrite particles were coated using a fluidized bed coating apparatus (Spiracoater SP-25 (Okada Seiko Co., Ltd.)). Thereafter, the manganese-based ferrite particles coated with the resin were fired at 220 ° C. for 1 hour to obtain a resin-coated ferrite carrier having a resin coating amount of 3 mass%.

(Mixing of toner and carrier)
The toner and carrier obtained in each of the examples and comparative examples were mixed under normal temperature and humidity conditions using a Nauta mixer so that the mass of the toner with respect to the mass of the two-component developer was 8.0% by mass. And mixing at 30 rpm for 30 minutes to obtain a two-component developer.

<Fixability evaluation>
Using the resulting two-component developer and toner, it has an aluminum fixing roller coated with PFA resin with a film thickness of 30 μm ± 10 μm and a surface roughness (Ra) of 5 μm, and the fixing temperature can be adjusted. Using a modified copying machine (TASKalfa 5550ci (manufactured by Kyocera Document Solutions Co., Ltd.)), a linear speed of 266 mm / second and a toner applied amount of 1.5 mg were set to form an unfixed solid image on a recording medium. The fixing temperature of the fixing device of the multifunction machine was increased from 100 ° C. by 10 ° C. in a range of 80 ° C. or higher and 200 ° C. or lower to fix an unfixed solid image. Using the obtained fixed image, the minimum fixing temperature and the maximum fixing temperature were measured based on the following measurement method. Fixability was evaluated according to the following criteria.
○ (Pass): The fixing lower limit temperature exceeds 100 ° C., and the fixing upper limit temperature is 200 ° C. or higher.
X (failed): The fixing lower limit temperature exceeds 100 ° C, or the fixing upper limit temperature is less than 200 ° C.

(Measurement method of minimum fixing temperature and maximum fixing temperature)
For a solid image formed by changing the fixing temperature by 10 ° C., the image density of the fixed solid image before and after the fastness test was measured, and the density ratio was calculated from the image density before and after the fastness test according to the following formula. The temperature at which a solid image having a density ratio of 80% or more could be fixed was defined as a fixing possible temperature. The lower limit of the fixable temperature was defined as the minimum fixing temperature. Further, the upper limit value of the fixable temperature was set as the fixing upper limit temperature. The fastness test was carried out using a Gakushin type friction fastness tester (JIS L 0849II type (manufactured by Yasuda Seiki Seisakusyo)) under a load of 200 g and a rubbing operation of 20 strokes. The image density was measured using a reflection densitometer (RD-918 (manufactured by Gretag Macbeth)).
Density ratio (%) = (image density after friction / image density before friction) × 100

<Method for evaluating heat-resistant storage stability>
3 g of the toner was weighed into a 20 ml capacity plastic container, the poly container was tapped for 5 minutes, and then left in a thermostat set at 55 ° C. for 8 hours to obtain a toner for heat resistant storage stability evaluation. After that, put a toner for heat resistant storage stability evaluation on a 300 mesh sieve (mesh size 48 μm), and follow the manual of a powder tester (manufactured by Hosokawa Micron Co., Ltd.), and screen with a rheostat scale of 5 hours for 30 seconds. went. After sieving, the mass of the toner remaining on the sieve was measured, and the degree of aggregation [%] was determined using the following equation.
(Cohesion calculation formula)
Aggregation degree [%] = (mass of toner remaining on sieve / mass of toner before sieving) × 100
Further, a toner for heat-resistant storage stability evaluation was obtained in the same manner as in the case where the temperature condition was 55 ° C. except that the temperature condition in the thermostat was changed to 60 ° C., and the degree of aggregation [%] was obtained.
The heat-resistant storage stability was evaluated according to the following criteria, and evaluations of “◯” and “Δ” were accepted and evaluation of “x” was rejected.
○: The degree of aggregation of the toner is less than 20%.
Δ: The degree of aggregation of the toner is 20% or more and less than 50%.
X: The degree of aggregation of the toner is 50% or more.

<Strength evaluation method>
0.1 g of toner, 20 g of zirconia beads having an average particle diameter of 1 mm, and 40 ml of ion-exchanged water were placed in a glass bottle having a capacity of 50 cc. Using a stirring mixer (TURBULA T2F type (Willy A. Bachofen AG)), the contents of the glass bottle were stirred and mixed for 5 minutes under a stirring condition of 90 rpm, and a toner strength test was performed. After the toner strength test, zirconia beads were separated from the mixture to obtain an aqueous medium dispersion containing toner particles. About the obtained aqueous medium dispersion liquid, the particle diameter and luminance value of the toner particles contained in the aqueous medium were measured using FPIA-3000 (manufactured by Sysmec Corporation). From the measurement results, the number (X) of toner particles having a particle diameter of 3 μm or more in the measurement sample using FPIA-3000 (manufactured by Sysmec Corporation), the particle diameter is 3 μm or more, and the luminance value is 100 or more. And the number (Y) of toner particles. The value of Y corresponds to the number of toner particles crushed by the strength test. The crushing rate [%] was determined using the following equation.
Crush rate [%] = (Y / X) × 100
The strength was evaluated according to the following criteria.
○: Crushing rate is less than 1.0%.
X: The crushing rate is 1.0% or more.

According to Examples 1 to 4, if the toner has ΔSP ₁ of 0.3 or more and 1.4 or less, ΔSP ₂ of 0.5 or more and 1.6 or less, and ΔSP ₁ is less than ΔSP ₂ It can be seen that the toner is satisfactorily fixed on the recording medium in a wide temperature range, and is excellent in heat-resistant storage stability and mechanical strength.

According to Comparative Examples 1 and 7, it can be seen that when ΔSP ₁ is larger than ΔSP ₂ , the obtained toner is difficult to be satisfactorily fixed on the recording medium in a low temperature range.

According to Comparative Example 5, when ΔSP ₁ and ΔSP ₂ are equal, the obtained toner is difficult to fix on a recording medium in a wide temperature range, and is inferior in mechanical strength.

According to Comparative Example 2, when ΔSP ₁ is excessively small, it can be seen that the obtained toner is not easily fixed to a recording medium in a high temperature range and is inferior in heat resistant storage property and mechanical strength.

According to Comparative Examples 3 and 6, when ΔSP ₂ is too large, it is found that the obtained toner is difficult to fix to a recording medium in a wide temperature range, and is inferior in heat-resistant storage stability and mechanical strength. .

According to Comparative Example 4, and 7, when whose ASP ₂ is too small, the resulting toner is seen to a low temperature region difficult to satisfactorily fix to the recording medium.

According to Comparative Example 8, when ΔSP ₁ is too large, the obtained toner is hardly fixed to the recording medium in a low temperature range, and the mechanical strength is inferior.

Claims (3)

A toner core particle containing at least a binder resin, and a shell layer covering the toner core particle,
The shell layer is composed of an inner layer and an outer layer,
ΔSP ₁ (SP _c −SP _t ), which is the difference between the SP value (SP _c ) of the binder resin and the SP value (SP _t ) of the material of the inner layer, is 0.3 or more and 1.4 or less. ,
ΔSP ₂ (SP _t −SP _s ), which is the difference between the SP value (SP _t ) of the inner layer and the SP value (SP _s ) of the material of the outer layer, is 0.5 or more and 1.6 or less,
The toner for developing an electrostatic charge image, wherein the ΔSP ₁ is less than the ΔSP ₂ .   The electrostatic image developing toner according to claim 1, wherein the binder resin includes a polyester resin.   The electrostatic image developing toner according to claim 1, wherein the outer layer contains one or more kinds of resins selected from the group consisting of (meth) acrylic resins and styrene- (meth) acrylic resins.